Will a dying or dead ignition coil-on-plug pack show a misfire code?

My 2003 3.0 liter petrol injected X-type with 102,000 miles started running a bit rough, with some mild loss of power while driving at about 45mph yesterday. It felt like it was driving on 5 our of 6 cylinders. It got a bit rougher with adding power, and decreased a bit with letting off the gas. It also showed a flashing ‘check engine warning’ icon. I was able to get it home (about a 4 mile drive) without problem and was able to do 55mph as usual, but with the constant flashing check engine icon. It briefly stopped for a few seconds and smoothed out on the drive, but started back up after about 30 seconds. When I got home, I checked the engine codes, and only showed a P1111 code, and when I cleared it, it then showed the P1000 code. It did not show any other codes. I’m thinking it is a coil pack.

First check to see if all your coil/plug leads are secure.
A few months ago I had rough running on my Subaru.
Eventually, the check engine light came on and my OBD II Scanner showed a misfire on #3 cylinder. A look under the hood showed the #3 lead was not fully inserted.
Pushed the lead back in the plug and the problem as fixed…
…Except every now and then the lead comes undone.
I’m getting another car soon so I’m not going to search any further.

While I doubt a lead has come loose (I have not messed with the engine at all in the past few years, other than oil changes), I will check for chafed wiring. The coil wiring connectors are ‘locked’ to the coils with tabs that are usually a PITA to get loose. I also have not noticed any obvious oil or water leaks around the engine area, or any ‘funny’ smells. EDIT: after starting the car up today, it is still mildly rough on giving it gas from idle in neutral, and after clearing the code(s) last night, the engine service light came back on today after revving the engine a few times. It gives a code of: P1316, and then also: P0306. Looking up the responses on the 'net, it appears there is a misfire…so I have ordered a new set of coils, as when one goes, others aren’t too far behind (so I’ve read).

One of the great things is that OBDII codes are the same for any vehicle. The problem can be looked up online without specifying the make, as it seems you may have already done. The first code Was P1316 which means the ECM is having trouble determining when to have the injector fire. Looking a little further online, found a little more elucidation for Jags in particular. The ECM can’t figure when to fire the injector because a misfire is occurring that is quite bad which could send unburnt fuel into the exhaust and cats. The second code P0306 says there is a misfire on cylinder 3. Could be a bad/cracked coil, wire, or even cracked plug. Fix the issue on 3 and all should be good.


I should have a new set of coil packs tomorrow, and I already have the new plugs, and a set of intake manifold O-ring seals to R+R the plugs/coils. Since the car has 100k miles, it is time for the routine plug change anyway.

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Latest/final update: I found that cylinder #1, which was the cylinder that was misfiring per engine code, had ‘filled’ with oil in the spark plug well. The spark plugs were good looking in all six cylinders. Apparently the spark plug area seal under the cam cover had been weeping for quite a while to fill the plug well, so I replaced the seals under the firewall side cam cover. I tried cleaning and degreasing the oil from the plug coil. I moved that coil pack to the front corner plug area so I could easily get to it if I need to permanently replace it. I put everything back together with new spark plugs, and new intake manifold seals. I didn’t replace the front cam cover seals, as I was kind of needed to get the car going before the next day. I started the car, and could tell that one cylinder was still misfiring. My OBD reader said the plug that the previously misfiring coil pack was on was now the problem plug. That proved to me that the coil pack was either taken out by the remaining small amount of oil, or possibly ruined by the previous misfiring somehow. I put a known good coil pack from my parts car X-Type in place of the bad one, and everything is now good.

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Good to hear. Thanks for letting us know how everything worked out.

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